XML 94 R77.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments (Equity and Debt Securities and Cash Equivalents and Cost Method Investments in Decommissioning Trust Funds) (Parenthetical) (Detail) - USD ($) $ in Millions | Sep. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Investment Holdings [Line Items] |  |
Fair value of securities in an unrealized loss position | $ 1,100 | $ 565
Net assets related to pending sales and purchases of securities |  | 5
Virginia Electric and Power Company |  |
Investment Holdings [Line Items] |  |
Fair value of securities in an unrealized loss position | 539 | 234
Net assets related to pending sales and purchases of securities | $ 1 | $ 6

X
- Definition This item represents net assets (liabilities) of pending sales (purchases) of investment securities. + References No definition available. + Details
Name: | d_NetAssetsLiabilitiesOfPendingSalesPurchasesOfInvestmentSecurities
Namespace Prefix: | d_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_InvestmentHoldingsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=d_VirginiaElectricAndPowerCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |